The simple tool could help health workers make faster decisions in developing countries, where people are sometimes far from doctor’s offices.

A test for anemia–a condition that makes you feel tired and weak because your blood isn’t carrying enough oxygen–usually involves going to a doctor’s office to have a needle stuck in your arm and an analysis of your blood via machine. But now doctors have invented a new way to screen for the condition using just a smartphone photo.

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It’s something that could be particularly useful in parts of the world where someone might not live near a medical office with the right equipment. “In certain parts of Africa or Asia, for example, their medical infrastructure is really poor, but the cell phone infrastructure is actually really good,” says Wilbur Lam, an associate professor of pediatrics at Emory University School of Medicine, and the lead author of a new article in Nature Communications about testing the software. “A lot of my colleagues who do global health work tell me their phone works better in certain parts of Kenya than in San Francisco. That’s because the mobile phone companies have leapfrogged right over the standard telephone line.”

[Image: Mannino et al./Nature Communications 2018]Doctors used an algorithm to analyze data from a photo of a fingernail. “It really works because of a couple of things–we couldn’t have done this a few years ago because the camera on cell phones wasn’t that great,” he says. “And there’s a lot more data now on cell phones.” The algorithm takes an image, along with metadata including color and lighting conditions, and then analyzes it based on what it has learned from similar photos to estimate levels of the healthy red blood cells that anemic patients lack. Over time, as the it gathers more data, the algorithm will keep improving.

It’s not as precise as a blood test, and can’t serve as a diagnosis. But in a global health setting, it can help a clinic understand if someone is either mildly or dangerously anemic. “They’re trying to figure out how to allocate rare resources–which of these people need to be ambulanced to a hospital right now, and whether they need a blood transfusion,” he says.

In the U.S., it could help pregnant women, who are at risk of anemia, test themselves easily from home. Parents can use it on young children, who are also at risk of anemia. Nursing homes could use it on the elderly. People who have chronic anemia because they have sickle cell disease, or kidney failure, or cancer patients will also be able to use it on their own. It’s something that could be very widely useful; anemia is so prevalent that it affects a quarter of the global population.

Now that it’s been proven to work, researchers are now working on making the app more user-friendly and then plan to release it next year. “What’s really exciting about this is because it’s just an app, we can get it out as fast as another app company,” Lam says. “So often when you’re talking about medical equipment and devices you’re talking about, okay, we’ve got the data, now we have to make a prototype, and then from that prototype, we have to manufacture. We don’t need any of that. This project is as nimble as the way Uber would change its interface.”

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About the author

Adele Peters is a staff writer at Fast Company who focuses on solutions to some of the world's largest problems, from climate change to homelessness. Previously, she worked with GOOD, BioLite, and the Sustainable Products and Solutions program at UC Berkeley, and contributed to the second edition of the bestselling book "Worldchanging: A User's Guide for the 21st Century."